class Maybe {
  static of (value) {
    return new Maybe(value)
  }
  constructor (value) {
    this._value = value
  }
  map (fn) {
    return this.isNothing() ? Maybe.of(this._value) : Maybe.of(fn(this._value))
  }
  isNothing () {
    return this._value === null || this._value === undefined
  }
} 
class Container {
  static of (value) {
    return new Container(value)
  }
  constructor (value) {
    this._value = value
  }
  map (fn) {
    return this.isNothing() ? Container.of(this._value) : Container.of(fn(this._value))
  }
  isNothing () {
    return this._value === null || this._value === undefined
  }
} 

module.exports = {Maybe, Container};
// module.exports = Container;